Whole Blood Platelet Aggregometry.

Light transmittance aggregometry is the historical reference method for platelet function testing and continues to be used extensively. Whole blood impedance lumiaggregometry represents an updated methodology that provides for simplified specimen management, an assay milieu that replicates in vivo platelet activation conditions, improved reproducibility, and near-patient testing. While the impedance-based whole blood aggregometer with luminescence channel is becoming the standard for platelet function testing using this methodology, at least three near-patient whole blood instruments are available, each employing its unique technology.

Measuring dabigatran with the dilute Russell viper venom confirm assay in an anticoagulation clinic population.

The dabigatran dose-response is predictable; however, it is necessary to measure plasma levels in a variety of clinical conditions. We evaluated a novel dabigatran measure - the 'dilute Russell viper venom confirm (DRVVC) assay' - against current developmental assays and a reference method. We measured plasma dabigatran and compared results from the Stago Sta-Clot DRVVC assay, Stago Ecarin Chromogenic Assay, Biophen Hemoclot Thrombin Inhibitor, and liquid chromatography tandem mass spectrometry.

Comparison of six dilute russell viper venom time lupus anticoagulant screen/confirm assay kits.

Background: The normalized dilute Russell viper venom time (DRVVT) ratio provides a robust assay methodology for lupus anticoagulant (LA) detection.

Objectives: We evaluated six normalized DRVVT LA screen and confirm systems for inter-method consistency. Reagents were purchased from Diagnostica Stago, Inc.

Career research opportunities for the medical laboratory scientist.

Medical Laboratory Scientists (MLS) typically practice in hospital laboratories; however there are multiple alternatives in research. This article details the advantages of working in a variety of research laboratory settings. These include public institutions, federal laboratory workplaces, private facilities, and industry settings.

Ability of the INNOVANCE PFA P2Y system to detect clopidogrel-induced ADP receptor blockade in preangiocath individuals.

We compared the ability of four test systems to detect platelet P2Y12 (ADP receptor) blockade by clopidogrel. The systems were the INNOVANCE PFA P2Y cartridge (PFA P2Y), the Accumetrics VerifyNow P2Y12 cartridge (VN P2Y12), whole blood aggregometry (WBA) using 5 (WBA 5) and 10 (WBA 10)  μmol/l ADP, and light transmittance aggregometry (LTA) using 20 (LTA 20)  μmol/l ADP. Blood was collected in 3.

Acinetobacter baumannii and MRSA contamination on reusable phlebotomy tourniquets.

Objective: A study was undertaken to determine the incidence of Acinetobacter baumannii and methicillin resistant Staphylococcus aureus (MRSA) contamination on reusable phlebotomy tourniquets at Wilford Hall Medical Center, Lackland AFB, TX.

Design: Reusable tourniquets (n=200) were collected after being used for one day in the outpatient blood collection center (n=100) or during morning blood collection rounds on inpatient wards (n=100). Tourniquets were cultured and growth was screened for A.

Effects of glucosamine and Celadrin on platelet function.

Objective: The purpose of this study was to determine the effects of glucosamine and celadrin on platelet function.

Design: Baseline values were determined on the Chronolog 570VS platelet aggregometer with whole blood aggregation impedance readings using 2 different concentrations of ADP (5 microM, 10 microM), collagen (1 microg/mL), arachidonic acid (0.5 mM/L) and an Accumetrics whole blood platelet aggregation cartridge assay for P2Y12 receptors were obtained from 24 healthy volunteers.

Duration of Loxosceles reclusa venom detection by ELISA from swabs.

Background: Diagnosis of Loxosceles reclusa envenomations is currently based upon clinical presentation. An enzyme-linked immunosorbent assay (ELISA) can detect surface Loxosceles venom at the envenomation site, allowing diagnostic confirmation. The length of time that venom on the skin is recoverable non-invasively is unknown.

Evaluation of four hematology and a chemistry portable benchtop analyzers using non-human primate blood.

Background: Near patient testing (NPT) and point-of-care testing (POCT) using portable benchtop analyzers has become necessary in many areas of the medical community, including biocontainment.

Methods: We evaluated the Beckman AcT diff, Abaxis Vetscan HMII (two instruments), Abbott Cell-Dyn 1800, and Abaxis Vetscan VS2 for within-run precision and correlation to central laboratory instruments using non-human primates blood.

Results: Compared with the central laboratory instruments, the Beckman AcT diff correlated on 80%; the HMII instruments on 31% and 44%, the CD1800 on 31%, and the VS2 on 71% of assays.

Whole blood platelet aggregometry and platelet function testing.

Platelet aggregometry has been the reference method employed to detect, diagnose, and monitor qualitative platelet disorders since the early 1960s. Lumiaggregometry and impedance-based whole blood lumiaggregometry have advantages over light transmittance aggregometry in that they provide for enhanced specimen management and increase the test sensitivity to impairment of platelet granule secretion. Whole blood lumiaggregometry detects and identifies congenital and acquired platelet plasma membrane receptor defects, metabolic pathway secretion disorders, and storage pool deficiency.

Comparison of a chromogenic factor X assay with international normalized ratio for monitoring oral anticoagulation therapy.

The purpose of the present study was to compare the international normalized ratio with a chromogenic factor X (CFX) assay for monitoring patients on oral anticoagulant therapy using the DiaPharma CFX method on a STA-R Evolution coagulation analyzer. International normalized ratio values were correlated with the CFX for determining normal, subtherapeutic, therapeutic and supratherapeutic ranges for these patients. Specimens were analyzed and grouped as normal or patients on oral anticoagulant therapy with international normalized ratios of less than 2.

Comparison of four laboratory methods to assess aspirin sensitivity.

The purpose of this study was to compare the ability of four commercial platelet function assays to detect aspirin response in normal individuals taking 81 or 325 mg aspirin in a single-dose response and then in a 7-day dosing regimen. We employed the Chronolog 570VS whole-blood aggregometer with agonists 1.0 microgram/ml collagen and 0.

Cutaneous and systemic effects of varying doses of brown recluse spider venom in a rabbit model.

Objective: To ascertain whether a dose response exists between the dose of brown recluse spider venom (BRSV) and the cutaneous and coagulation effects in a rabbit model. Cutaneous necrosis is a serious complication of brown recluse spider envenomation (spider bite with venom). Disseminated intravascular coagulation (DIC) is a dreaded complication of brown recluse envenomation in humans.

Effects of different aspirin formulations on platelet aggregation times and on plasma salicylate concentrations.

Background: Early aspirin treatment is widely used to inhibit platelet activity and to reduce morbidity and mortality in patients presenting with an acute myocardial infarction or a stroke. A number of different aspirin formulations have been used for this purpose; however, a comparison of their effectiveness in inhibiting early platelet aggregation has not been determined.

Methods: In this study, we determined plasma salicylate concentrations and platelet inhibitory activities at various times after ingestion of three commonly used aspirin formulations: soluble aspirin (Alka-Seltzer), 325 mg, chewed baby aspirin, 324 mg, and whole compressed non-enteric coated aspirin, 324 mg.

Oral health screening using a caries detection device.

Children from low-income families are more likely to have dental disease and less likely to have regular dental care. Children's dental-related illnesses are responsible for more than 880,000 lost school days each year. The lack of reliable state-level data often makes monitoring the oral health of children a challenge.

Comparison of colchicine, dapsone, triamcinolone, and diphenhydramine therapy for the treatment of brown recluse spider envenomation: a double-blind, controlled study in a rabbit model.

Objective: To compare the efficacy of dapsone, diphenhydramine, colchicine, and intralesional triamcinolone in the treatment of brown spider bites. We used a purified venom that reproducibly produces a large eschar. To mimic real-life circumstances, all agents were administered following a 2-hour delay after envenomation.

Effects of pre-analytical variables on the anti-activated factor X chromogenic assay when monitoring unfractionated heparin and low molecular weight heparin anticoagulation.

The purpose of this study was to determine whether the anti-activated factor X (anti-FXa) assay is less affected by pre-analytical variables in monitoring patients on unfractionated heparin (UFH) and low molecular weight heparin (LMWH) than the activated partial thromboplastin time (aPTT). Forty-six subjects receiving either enoxaparin (LMWH) or UFH were randomly selected. Each study subject had six vacutainer tubes (3.

A comparison of INRs after local calibration of thromboplastin international sensitivity indexes.

Unlabelled: There are approximately 300 reagent/instrument combinations for performing prothrombin times/international normalized ratios (PT/INR) in the United States. Manufacturers and laboratories continually struggle to ensure that the International Sensitivity Index (ISI) of their thromboplastin is accurate for assaying PT/INR.

Objective: This study reports the feasibility of a new method to locally calibrate ISI of thromboplastin using the mechanical STA automated coagulation analyzer (Diagnostica-Stago Inc.

Antiphospholipid antibodies and stroke in young women.

Background And Purpose: Antiphospholipid antibodies have been associated with ischemic stroke in some but not all studies.

Methods: We performed a population-based case-control study examining antiphospholipid antibodies (anticardiolipin antibodies and lupus anticoagulants) using stored frozen sera and plasma in 160 cases and 340 controls enrolled in the Stroke Prevention in Young Women study. We evaluated for the presence of anticardiolipin antibody (IgG, IgM, and IgA isotypes) by an enzyme-linked immunosorbent assay and for the lupus anticoagulant using several phospholipid-dependent coagulation tests (activated partial thromboplastin time, dilute Russell's viper venom time) with mixing studies.

Facilitation of recovery from acute blood loss with hyperbaric oxygen.

Background: Hyperbaric oxygen (HBO) has been used for more than 25 years as therapy for extreme blood loss in cases where transfusion has been unavailable. The use of HBO for lesser amounts of blood loss to avoid the transfusion of blood products has not been investigated.

Hypothesis: Hyperbaric oxygen up-regulates hemoglobin synthesis after acute blood loss in an animal model of moderate (30%) blood loss.

Neuropsychiatric syndromes in lupus: prevalence using standardized definitions.

Objective: The San Antonio Lupus Study of Neuropsychiatric Disease is a longitudinal study designed to characterize the spectrum of and important risk factors for specific neuropsychiatric systemic lupus erythematosus (NPSLE) syndromes.

Methods: Subjects must meet criteria for SLE and must be at least 18 years of age. A standardized medical history, neurologic, rheumatologic, and psychiatric examinations, computerized neuropsychological evaluation, and serologic testing are performed.

Histological findings after brown recluse spider envenomation.

Histologic specimens from 41 rabbits were studied for changes resulting from the manual injection of brown recluse spider venom. Major findings included a mixed inflammatory cell infiltrate, coagulative tissue necrosis, and vasculitis. All specimens demonstrated a well-delineated zone of eosinophilic staining recognizable as "mummified" coagulative necrosis of the epidermis and dermis.

A review of variables affecting PTs/INRs.

The prothrombin time is a common method of monitoring patients undergoing oral anticoagulant therapy. The proliferation of commercial thromboplastin brands with different international sensitivity indices (ISI) in conjunction with wider availability of automated coagulation analyzers has elevated the need for standardization in monitoring therapy.